It'll probably be near the end of the month, they usually have announcements end of January/start of February time but they seems to be doing smaller announcements every few weeks now so it's possible it could be sooner
You could say that about a lot of “legacy” headliners at most festivals all over the world.
When was the last time the Rolling Stones released anything of note for example 🤷♂️ ….. A lot further back than muse.